Pavement



Jan 20, 1931- A. o. M. PADDLEFORD 1,789,447

PAVEMENT Filed May 17 1926 Inman/fr:

Patented Jan. 20, 19u31 UNITED STATES PATENT OFFICE omvrzriI n. Panoramen, or HUNTINGTON man, cennzoncwrnv PAVEMENT v Application ma nay 17, 192s. serial No. 109,510.

This invention relates to pavements and particularl to surfacing of roadwa s and the like.

provision of a pavement which will protect i* the foundation from cracking,'break1ng up,

tinuous rough usage thereof does not produce its.

A urthe'r object is the provision of a surfacing which will increase the life of the sub-base. A further object is the provision of a pavement wherein the dierent solid particles thereof are cushioned from one another and whereby such solid articles, which may be rock, are revented such rocks ru bing against one another when the pavement is m actual use -or holding heavy loads.

The invention has for further objects the provision of a pavement which is simple of.

manufacture inexpensive in construction and very durable and generally superior to pavements now used. f

The drawing illustrates in vertical section my improved pavement. My pavement is directlyy applicable for the surfacing of sub-bases, although it will be obvious that the type of pavement I am about to describe may be lplaced upon a suitable foundation providing'this foundation is sufficiently hard and firm.

In the making of a pavement I use some vmaterial which will surround the diierent is a wave movement in the pavement. Al.

though ,this movement may be slight, nevertheless the effect upon the rocks is, one that is deleterious, for the reason that the 'grinding process continuesuntil pits are made in 'the pavement. Furthermore, it lis necessary that this cushioning material should have he invention has for an object the om pulverizing by' non-compressible properties, Aand preferably be somewhat resilient 1n nature.

I may use in the present avement rocks 'of diiferent sizes, and I pre erably provide three graded sizes of rocks.v For instance, I use rocks which are hard, such as a granite type of rock, and the rocks are broken up and placed within a drum which isrotated and directs the rocks onto three different sizes ofto further screens which would select the half inch rocks, and such rocks aswould lie between a quarter inch and a half inch' and also all rocks that would lie .between a half inch and one inch in size. form of rotary separator for rocks might e used and these rocks are collected in accordance with their different sizes.

The next step consists in providing the velvet material or the cushioning material that lies between the rocks to separate the same, and I may use for this purpose clay which'is free from any material that would damage asphaltum. To this end the clay must be free from acids and of such a nature as to be extremely soft and fine.L Clay, such as used in the making of' ottery may be used, andI select the clay y applying the following test, viz': pulverized' clayafter being freed from any material that would dama e as'phaltum, 50 per cent of same must pass t rough a 100 mesh screen, and furthermore, it must be that quality o f clay which when passed through the 100 mesh screen, per cent of the same will, 4when washed with water, pass through a 200 mesh screen. Havingselected the clayI then select a certain percentage of the' different sizes' of rocks. I may use various percentages of,

clay rocks and asphaltum to meet varying con itions the mamv principle being to provide a suiicient 'percentage of asphaltum to act as a binder for the rocks and clay, but I have found the following percentages adaptable for most conditions, namely, from 15 to 40 per cent clay, 5 to 15 per cent asphaltum, fine mineral aggregate bemg that size of rock which would pass through a quarter inch screen and retained on a 2O mesh screen;

^ medium mineral aggregate being that size which would pass through a half inch screen 5 and retained on a quarter inch screen; and

coarse mineral aggregate of a size that would pass through a one inch screen and be retained on a half inch screen. The percentages of the different mineral aggregates would in each instance vary from 2O to 4() per cent. The rocks are first heated and then they are mixed in the percentages named with the clay, and while the rocks are hot. The hot asphaltum is then added to the rocks and clay and the entire mass thoroughly agitated. In actual practice a machine may be provided, one side of which contains hot asphaltum and the other side of which has a bin withinwhich. are the mixed rocks and clay which have been heated, and

.between lthe bin for the rocks and the clay and the container for the hot asphaltum are paddles which are rotated to thoroughly mix the asphaltum and the rocks and clay. The

mixed asphaltum, rocks and clay are then deing sizes, are shown at 3. These rocks are separated by the cushion material 4 in combination with asphaltum. Rolling the mix while it is hot tends to press the rocks away from the surface and present a thin layer of asphaltum for the immediate top surface as shown at 5.

Acids have a bad effect upon asphalt, in that acids tend to eat the asphaltum and render the pavement structure weak, with 4the result that the rocks are allowed to contact and abrade one another, and pits and cracks occur in the pavement. As I have previously stated, the pavement ymaterial that I have described'y is intended primarily for use as a pavement surfacing. However,

it may be used as a sub-base providing the foundation is suiiiciently firm and hard. If the surfacing is placed upon concrete, it will be obvious that the concretewill be protected. Concrete being very hard tends to rut easily if a heavy load'is impacted suddenly thereon. My surfacing, however, gives a cushioning e ect, and thus the blow is revented from damaging the concrete there eneath.

Sand cannot be used in the present invention, because sand compacts, and furthermore, for the reason that sand is simply small rocks. My concept and inventlon requires the use of a material between the rocks which will not stay compressed, and

while I have described clay as one of such materials, yet it is obvious that other materials of like nature and with like properties might be used.

Having thus disclosed my invention, I claim and desire to secure by Letters Patent:

1. The method of constructing a roadway which consistsin first preparing a paving material by heating rocks and clay and separately heating asphaltum, then mixing the hot asphaltum with the hot'clay and rocks whereby the clay and asphaltum combine to produce an elastic adhesive mixture separately encasing each rock, then pouring the mass while hot upon the roadway and then rolling the mass while it is hot.

2. The method of preparing a paving material which consists in heating rocks and clay and separately heating asphaltum, then mixing the hot asphaltum with the hot clay and rocks whereby the clay and asphaltum combine to produce an elastic adhesive mixture separately encasin each rock. .y

In testimony whereo I have signed my name to this specification.

OLIVER M. PADDLEFORD. 

